Human herpes simplex virus (HSV) lies dormant in the human sensory ganglions. Once one is infected, the disease recurs repeatedly. There are two types in HSV: Type I and Type II. The rate of recurrence and the sensitivity to drugs differ depending on the type. Therefore, the determination of the type of HSV is important. The most reliable method of diagnosis of the HSV infectious disease is to isolate the virus for determination, but this method requires culture cells and requires several days for the determination, so is difficult to appropriately reflect the results in treatment. There is also a method of determination using a fluorescent antibody, but in this case cells of the diseased area are required. Further, there is known a method of using DNA fragments type-specific to HSV as a probe and examining a sample of the patient by the dot blot method. Nevertheless, this method does not only require a lot of sample (for example, 200 to 500 .mu.l), but also was not able to determine the type of HSV, even when HSV was found. Therefore, there has been a desire for the development of a technique and in vitro diagnostic agents which enable determination of HSV I and HSV II with high precision in a short time.
On the other hand, while it had been said in the past that there was no base sequence which would enable type-specific recognition of HSV, the present inventors have already developed a type-specific DNA probe for HSV. Namely, it is possible to obtain a type-specific DNA probe by labeling DNA fragments obtained by cleaving HSV I or HSV II DNA with particular restriction enzymes [or DNA fragments obtained by cleaving DNA obtained by inserting the DNA fragments into an appropriate vector (plasmid) and cloning the same, with particular restriction enzymes]. These labeled DNA fragments include several hundred to several thousand bp (base pairs) and are superior in type-specificity. Details thereof are disclosed in Japanese Unexamined Patent Publication No. 2-142499 and Japanese Patent Application No. 2-90198.
However, the above-mentioned labeled DNA fragments have a size difficult to prepare by chemical synthesis. Therefore, the present inventors engaged in further studies to discover base sequence which can be easily handled (for example, a size to an extent that chemical synthesis can be adopted) without reducing type-specificity. As a result, a relatively small base sequence which can be used in type-specific determination was discovered. Namely, the object of the present invention is to provide various primers which can be used for the amplification of DNA fragments specific to HSV I or HSV II, and probes specific to HSV I DNA or HSV II DNA.